A car columnist spends half a decade testing the fastest, swankiest, most technologically advanced rides on the road - and declares a winner.

(Business 2.0 Magazine) -- After five years of writing this column, I'm about to shed all objectivity. Before I do, however, let's review some numbers. During the past half decade, I've tested - though not always written about - almost 200 cars, worth a cumulative $20 million or so. Although I've logged as many as 1,000 miles in a single car, on average I've driven the things between 100 and 200 miles before handing them back to their corporate overseers, thus clearing the decks for the next new ride.

This translates into 30,000 miles of hands-on experience with some very expensive iron. (Happily, I've not wrecked a one.) When people discover that you've done time in almost every nice car in existence, they tend to ask which is your favorite. To date, I've ducked the question. But now, at long last, I'm ready to spill. So, Audi, could you please send me one 2008 S6 sports sedan, preferably in phantom black? It's my kind of car.

The FSI V-10 cranks out 435 HP, enough to thrust the S6 to 155 mph and beyond.

A brief caveat. Were money and highway patrolmen not factors, my choice would be the $1.4 million Bugatti Veyron. But since they are, I've settled on something more sensible. Not that the S6 doesn't scoot. Audi took its race-proven 5.2-liter FSI V-10 engine - a brutish power plant similar to the one used in the Lamborghini Gallardo - and camouflaged it within the S6's demure sedan form.

FSI is an acronymic way of designating that this engine utilizes a high-tech fuel-injection system wherein precisely measured and atomized gasoline is blasted directly into the combustion chambers, a technique that boosts torque and horsepower and ups the engine's overall weight-to-power efficiency.

Though it weighs but 485 pounds, Audi's V-10 cranks out 435 horsepower, more than enough to effortlessly thrust the S6 to 155 mph - and far beyond, were the engine not electronically limited. Unfortunate, that.

Over the past two years, Audi has been on a repositioning jag, introducing 17 new or redesigned models aimed at seducing every conceivable sector, from speed demons (see the R8, which flirts with 200 mph) to luxury lovers (note the A8, which can top $140K). In many ways, the S6 is the aggregate of them all: a proto-ride as swift and sure-footed as the best sports cars and as swank as the most bespoke sedans.

The S6 is based on the A6, Audi's midrange offering, which allows that sedan's buttoned-down anonymity to work to its favor. Both the A6 and the S6 are smooth-lined studies in understatement, with only a few visual clues to distinguish the hard-charging S from the lesser A. (The S6 sports a tasteful apostrophe of a spoiler and a wicked set of LED daytime running lights tucked beneath the front bumper.)

As expected from an Audi, the S6 has quattro all-wheel drive, but Audi's engineers reapportioned the torque split asymmetrically, with 60 percent rearward and 40 percent forward, thereby giving rear-wheel-drive overtones to the S6.

Sensors ping this system hundreds of times a second, and should you, in your twisty road enthusiasm, start to get squirrelly, the car will instantly tweak those ratios - also the traction control, differential, and so on - to make certain that things stay extraordinarily stable. If you'd prefer an analogy, try this: Piloting an S6 feels as if you've somehow gained control of a high-speed monorail.

Of course, that's not the only reason the car pleases me so much. One consequence of tooling around in Bentleys and Ferraris and Maseratis is that -poor me - you get stared at a bunch. Fast cars tend to be flashy, for reasons too Freudian to trouble with here. But take a quick gander at the above picture. Nothing showy there, despite the mechanical muscle. The S6 is the automotive equivalent of dressing a UFC champion in a nice black suit.

That refinement continues into the cabin, which is - again with the superlatives - probably the best I've encountered. While it's not the most opulent (check out the Rolls-Royce drophead coupe sometime), the S6 is a seamless accommodation of both cost and cush. A bit of birch, a bit of carbon fiber, a bit of hand-stitched leather - it all meshes.

The high-back bucket seats have integrated headrests and massive bolsters and look as if Charles Eames had designed them. In fact, Modernism defines the cabin, which is cool, clean, and exactingly unfussy. (If Steve Jobs did car interiors, he'd create something like this.) Audi even employs salaried smellers to ensure that the interior of every S6 has a consistent and pleasant aroma.

I could go on - did I mention the back-up camera, the servo steering, the adaptive headlights, the keyless start? - but you get the drift. Also, the overseers are coming to take the S6 away, and what with all the gushing, I'm in serious danger of losing my long-cultivated mask of editorial sangfroid.